I guess Cannadine was only talking about Marxisim in a rather limited sense, the class concept. Other historians in the congress mentioned that Marxist and Neo-Marxist perspectives might be useful now in this global crisis of capitalism.
I don’t know, ever since I started reading about Marxism I’ve been very conflicted about it. There are a lot of things that don’t seem to hold up and yet it’s such a useful and readily accessible tool for analysis. In history any sort of theory must be bent to the empirical evidence at hand, not the other way around. The same should apply for political thought.